-normal inputs: inputs from the CAPT, F/O, 3rd OCCPNT , Avionics Bay (and optionally 5th OCCPNT)
 -protected inputs: they comprise the mechanic input and the Reserve input (input 6).

 (b)
 Protected inputs The mechanic input is disconnected from the interphone amplifier when the flight/ground information from the LGCIU is present (flight configuration). The input 6 is disconnected from the interphone amplifier when the PTT input 6 is not activated.

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 Flight Interphone - Block Diagram
 Figure 030A

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 (c) Architecture The adaptation board perfoms the summing of all the modulation signals. As a security precaution, there are two independent summation circuits. The output of the first summation circuit is transmitted to the "master" audio board (board A). The output of the second summation circuit is transmitted to the "slave" audio board (board B).
 NOTE : The ouputs of the first summation circuit is also
____ transmitted to the MECH and Audio 6 outputs.
 (3) Not Applicable

R **ON A/C 001-049, 051-099, 101-105, 151-199, 201-220,
 (4) Logic Processing Function
 (Ref. Fig. 031)

 (a)
 Purpose Each user of the audio integrating system has an associated logic-processing channel. The logic processing function manages the processing channel at AMU level and enables the use of the system. In particular:

 -
It dialogs with the associated ACP, with the BITE circuit or the SELCAL-CALL circuit.

 -
It manages the various inputs/outputs of the processing channel.

 (b)
 Composition
 The logic processing channel comprises:

 -A computer
 -An interface circuit to ARINC 429 standard
 -
A serial interface circuit

 -
A control interface circuit.

 1 Computer
_ It comprises the peripherals required for the operation of the microprocessor, clock, monitoring circuit (watchdog), memories, address decoder, etc.
 2 ARINC 429 interface
_ This circuit ensures the interface with the ACP and comprises: a transmission interface, a reception interface, a microprocessor interface.
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 Logic Processing - Block Diagram
 Figure 031

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 -Transmission interface The transmission interface conditions the electrical levels in compliance with ARINC 429 standard.
 -Reception interface The reception interface enables the galvanic insulation of the link between the ACP and the AMU. It also reconstitutes the transmission clock and the information.
 -Microprocessor interface Transmission: this interface receives data in byte form from the microprocessor. This data is required to transmit the messages and to condition them in compliance with ARINC 429 standard. Reception: this interface receives the transmission clock and the data in ARINC message form. It transmits this data to the microprocessor in byte form.
 3 Serial interfaces
_ These interfaces enable data exchange between the logic processing function and the BITE and SELCAL-CALL functions. These interfaces are mainly comprised of 2 ACIAs (Asynchronous Communication Interface Adaptors).
 4 Command interface
_ This interface comprises PIAs (Peripherals Interface Adaptors) or buffer registers. The microprocessor uses them to acquire discrete information (e.g. PTT switches) or to generate commands. These commands are sent to the various functions
 (e.g. transmission selection command, setting into service of VOICE/ON filter).

R **ON A/C ALL
 F. SELCAL Function - Mechanic Call - Cabin Attendant Call
 (1) Purpose The SELCAL-CALL system of the audio management system gives :
 -
A visual and aural indication of the calls from the ground stations equipped with a coding device which can be used by the aircraft installation (SELCAL system - Selective Calling). The calls are sent on the radio frequencies which link the aircraft to the ground. The communication channels used are : VHF1 - VH2 and VHF3, HF1, HF2 if installed.

 -
A visual indication of the calls from the ground crew or from the Cabin Attendants.

 NOTE : The ground crew call system is described in chapter 23-42-00:
____
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 "Cockpit-to-ground crew call system" (circuit WC).
 The Cabin Attendant call system is part of chapter 23-73-00:
　
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